Odor control

J. P. Cox, Odor Control and Olfaction, Pollution Sciences Publishing Company, Lynden, Washiagton, 1975. 

Proceedings, State of the Art of Odor Control Technology Specialty Conference, March 1974, Air Pollution Control Association, Pittsburgh, Pa., 1974. 

Odors are measured by their intensity. The threshold value of one odor to another, however, can vary greatly. Detection threshold is the minimum physical intensity necessary for detection by a subject where the person is not required to identify the stimulus, but just detect the existence of the stimulus. Accordingly, threshold deterrninations are used to evaluate the effectiveness of different treatments and to estabflsh the level of odor control necessary to make a product acceptable (8). Concentration can also produce different odors for the same matenal. For example, indole (qv) in low concentrations has the smell of jasmine and a low threshold of perception. In high concentrations, it has a strong odor of feces and CX-naphthyl amine as well as a considerably higher threshold of perception. 

Taste and Odor Control. Tastes and odors in surface waters result from the action of biological organisms, eg, algae, or from various minerals, pollution by industry, domestic seepage, or agriculture. Groundwaters may have taste and odor if they are polluted or if they contain gases, eg,... 

Stormwater overflow is chlorinated, and in some plants the influent may be chlorinated for odor control. 

Uses. /-Butyl hypochlorite has been found useful in upgrading vegetable oils (273) and in the preparation of a-substituted acryflc acid esters (274) and esters of isoprene halohydrins (275). Numerous patents describe its use in cross-linking of polymers (qv) (276), in surface treatment of mbber (qv) (277), and in odor control of polymer latexes (278). It is used in the preparation of propylene oxide (qv) in high yield with Httle or no by-products (269,279). Fluoroalkyl hypochlorites are useful as insecticides, initiators for polymerizations, and bleaching and chlorinating agents (280). 

In terms of an economic determination, gas temperature adjustment is often the most important cost factor in determining whether to use a biofilter or a more conventional system. If the process gas stream is at an extremely high temperature (-i-I00° C), the cost of cooling the inlet gas stream might favor more conventional methods for odor control such as thermal oxidation. 

Odor control by the addition of dilution air involves a problem associated with the breakdown of the dilution system. If a dilution fan, motor, or control system fails, the odorous material will be released to the atmosphere. If the odor is objectionable, complaints will be noted immediately. Good operation and maintenance of the dilution system becomes an absolute requirement, and redundant systems should be considered. 

Engineering Considerations To effect the good engineering design of an activated carbon adsorption system, it is first necessary to obtain information on the following the actual cubic feet per minute (ACFM) of air to be processed by the adsorber, the temperature of gas stream, the material(s) to be absorbed, the concentration of the material to be adsorbed, and if the intended application is air pollution control such as odor control - then the odor threshold of the material to be adsorbed. In addition, data is needed on the presence of other constituents in the gas stream, and whether or not solvent recovery is economical. 

Bameby Sutcliffe Site describes company providing activated carbon, air purification, solvent recovery, emission control, remediation, odor control, corrosive gas control, pollution control, air filterr, and distillation equipment. http //www.bscarbons.com... 

The first application of chlorine in potable water was introduced in the 1830s for taste and odor control, at that time diseases were thought to be spread by odors. It was not until the 1890s and the advent of the germ theory of disease that the importance of disinfection in potable water was understood. Chlorination was first introduced on a practical scale in 1908 and then became a common practice. 

Figure 13.Example of a municipal water treatment plant for taste and odor control.

Chlorine dioxide uses expanded rapidly in the industrial sector. In 1944, chlorine dioxide was first applied for taste and odor control at a water treatment plant in Niagara Falls, New York. Other water plants recognized the uses and benefits of chlorine dioxide. In 1958, a national survey determined that 56 U.S. water utilities were using chlorine dioxide. The number of plants using chlorine dioxide has grown more slowly since that time. 

At present, chlorine dioxide is primarily used as a bleaching chemical in the pulp and paper industry. It is also used in large amounts by the textile industry, as well as for the aching of flour, fats, oils, and waxes. In treating drinking water, chlorine dioxide is used in this country for taste and odor control, decolorization, disinfection, provision of residual disinfectant in water distribution systems, and oxidation of iron, manganese, and organics. The principal use of chlorine dioxide in the United States is for the removal of taste and odor caused by phenolic compounds in raw water supplies. 

The odor control market is the largest and much of this market is in sewage treatment plants. Use of ozone for odor control is comparatively simple and efficient. The application is for preservation of environmental quality in addition, alternative treatment schemes requiring either liquid chemical oxidants (like permanganate or hydrogen perioxide) or incineration can significantly increase capital and costs. 

Ozonation The application of ozone to water, wastewater, or air, generally for the purposes of disinfection or odor control. 

Adsorption is the most widely used solvent-recovery technique and is also used for odor control. The latter application is necessary to meet statutory air pollution control requirements. Depending on the application, adsorption can be used alone or with other techniques such as incineration. " ... 

Odor control The elimination of odor in a space by the use of masking chemicals or special filters. 

Titania photocatalyst is used for air and water purification, photo-splitting of water to produce hydrogen, odor control and disinfectant. Crystal structure and crystallite size of titania particles are one of the most important factors that affect on the photoactivity. Photoactivity of anatase is higher than that of rutile, and increases with crystallite size [1]. Therefore, to increase photoactivity, it is desirable to find a route for the synthrais of the pure anatase titania with large crystallite size. 

Adsorption traditionally has found wide application in the field of odor control. Odors are generally created by the... 

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